In real life, objects such as remote controllers or fruit knives are frequently used but are often placed carelessly. People sometimes may forget where these objects are placed or these objects may be moved by other persons and cannot be found. This may create unnecessary troubles for users.
In some applications, sound activating method is used for finding objects. Specifically, a sound-activated device is disposed on an object. When a trigger condition is satisfied, the sound-activated device on the object is turned on to make sounds. Thus, users can find the object.